Старт нового Activity с помощью spinner?

public class MainActivity implements AdapterView.OnItemSelectedListener {
    ...
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ....
        Spinner spinner = (Spinner) findViewById(R.id.spinner);
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.planets_array, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);
    }

    ...

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        parent.getItemAtPosition(position);
        switch (position) {
            case 0:
                return;
                //этот будет срабатывать сразу при отображении спиннера
            case 1:
                Intent intent = new Intent(this, Main2Activity.class);
                startActivity(intent);
                return;
            case 2:
                Intent intent = new Intent(this, Main3Activity.class);
                startActivity(intent);
                return;
        }
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }

}

<string-array name="planets_array">
        <item>Mercury</item>
        <item>Venus</item>
        <item>Earth</item>        
</string-array>